Transmitter, signal transmitting method, and data distributing system for transferring a content signal or processing copyright protection on a content signal

ABSTRACT

To enable usage of content at a receiver which does not have a copying function even if copyright protection is provided. Model names of receivers not having a copying funtion are held in an authentication processing circuit of a transmitter. When a model name obtained from a connected receiver is held, regardless of whether the content is copyright protected, a signal selection circuit selects a terminal a side, a switch is turned on, and an unencrypted signal is transmitted. When a change of the receiver is detected by a hot plug detection or plug and play function at a processing circuit during the signal transfer of copyright protected content without providing copyright protection, the selection circuit selects a terminal b side or the switch is turned off to suspend the transfer of the non-copyright protected signal. The information indicating the receiver is held in a tamper-proof updateable manner.

TECHNICAL FIELD

The present invention relates to a transmitter, signal transfer method,data distribution system and method of same, data receiver, dataprovider and method of same, and data transferee. More specifically, thepresent invention relates to a technology for holding in advanceinformation indicating a receiver which does not have the function ofbeing able to copy content using a transferred content signal, andcontrolling the transfer of a content signal of content or a copyrightprotected content signal according to whether or not informationindicating a connected receiver is included in the held information atthe time of transfer of the content.

BACKGROUND ART

In the past, a computer system etc. has converted a digital image signalto an analog image signal and supplied the same to a display device byanalog transmission. However, along with the spread of display devicesfor driving displays by using a digital signal, for example, liquidcrystal displays, the method of digitally transferring a digital imagesignal without converting the same to an analog signal for preventingdegradation of the quality of the image or reducing costs has beenstandardized. For example, the DDWG (Digital Display Working Group) isformulating a DVI (Digital Visual Interface, Version 1.0) specification.This DVI specification uses a TMDS (transition minimized differentialsignal) channel developed by Silicon Image Corp. of the U.S. to seriallytransfer a digital three-primary color image signal by the baseband forevery color.

FIG. 4 is a conceptual view of a signal transfer system for transferringa digital image signal of content by using a channel of the DVIspecification. A transmitter (for example a computer system or set topbox) 20 for transmitting the image signal and a receiver (displaydevice, television system, etc.) 50 for receiving the image signal anddisplaying the image are connected via channels 30 of the DVIspecification. In a DVI specification channel, not only is a TMDSchannel for transferring a digital image signal used as mentioned above,but also a bi-directional channel (I²C bus or the like) used forinformation transfer in a DDC (display data channel) specificationrelating to plug and play established by VESA (Video ElectronicsStandard Association) is provided.

Here, if a transmission controller 25 of the transmitter 20 detects thatthe receiver 50 has been connected, the transmission controller 25communicates with a reception controller 53 of the receiver 50 accordingto the DDC protocol, controls an image signal generator 21 based onreceiver information obtained from the reception controller 53, forexample, information of a model name and resolution of the receiver 50,and generates a digital three-primary color image signal optimum for thereceiver 50. The three-primary color image signal DG is supplied to atransmission processor 22 comprised by using a TMDS transmissioncircuit. The transmission processor 22 generates a baseband serialtransfer signal SD from the supplied three-primary color image signal DGand supplies it to the receiver 50 from a connector 27 via the channel30. The receiver 50 supplies the serial transfer signal SD supplied viaa connector 51 to a reception processor 52. The reception processor 52is comprised by using a TMDS reception circuit and generates the digitalthree-primary color image signal DS from the serial transfer signal SDand supplies it to an image display 54. For this reason, the imagedisplay 54 can optimize and display an image of the content based on thethree-primary color image signal DS.

Since the content transferred via the channel 30 of TMDS is converted tothe digital signal, a perfect copy can be prepared easily andlimitlessly. This is a great advantage for the user, but a problem interms of protecting the rights of the side providing a movie or otherwork. For this reason, a proposal referred to as “DVI-CP (ContentProtection)” using encryption technology for copyright protection whentransferring a digital signal of content by using a DVI specificationchannel has been made by Intel Corporation of the U.S.

FIG. 5 is a conceptual view of a signal transfer system for transferringa signal of content compatible with the DVI-CP specification. The imagesignal generator 21 of a transmitter 20 a has a protection informationdetector 23 connected to it. This protection information detector 23decides the digital three-primary color image signal DG to betransferred includes protection information indicating that the signalis one of content to be copyright protected. When this protectioninformation detector 23 detects the protection information (when it isdecided that the content is to be copyright protected), an encryptioncircuit 221 provided in a transmission processor 22 a encrypts thethree-primary color image signal DG and provides this encrypted signal,that is, the three-primary color image signal DGE, to the TMDS signalcircuit 222, to generate the serial transfer signal SD.

Also, a reception processor 52 a of a receiver 50 a is comprised byusing not only a TMDS reception circuit 521, but also a decryptioncircuit 522. The TMDS reception circuit 521 receives the serial transfersignal SD, generates a three-primary color image signal, and supplies itto the decryption circuit 522 for the decryption processing. Here, atransmission controller 25 a of the transmitter 20 a and a receptioncontroller 53 a of the receiver 50 a perform processing for mutualauthentication according to the DDC protocol and, when deciding that acorrect party is connected, supply the encryption key DC used for theencryption of the three-primary color image signal DG to the decryptioncircuit 522 to enable the decryption circuit 522 to correctly decryptthe encrypted three-primary color image signal. The digitalthree-primary color image signal DG obtained at this decryption circuit522 is supplied to the image display 54. Even if the three-primary colorimage signal DG is transferred encrypted, the image of content can becorrectly optimized and displayed on an image display 3.

Also, since the serial transfer signal SD is generated based on theencrypted three-primary color image signal DGE, the unencryptedthree-primary color image signal DS cannot be obtained just by receivingthe serial transfer signal SD, so the content can be prevented frombeing digitally copied as it is.

If, however, encryption technology for copyright protection is added tothis DVI specification and becomes standard after use of receivers 50based on the above DVI specification starts, when a transmitter 20 abased on the new specification encrypts and outputs a digital imagesignal, a prior DVI specification receiver 50 sometimes will not be ableto display the image since it does not have the function of decryptingan encrypted digital image signal.

For example, as shown in FIG. 6, when outputting a digital image signalfrom a transmitter 20 based on the conventional DVI specification as aserial transfer signal SD, both a receiver 50 based on the conventionalDVI specification or a receiver 50 a based on the new specificationincluding the encryption technology can display the image of thecontent. Also, when outputting a digital image signal from a transmitter20 a based on the new specification including the encryption technologyas the serial transfer signal SD, a receiver 50 a having the function ofdecrypting an encrypted digital image signal can display the image ofthe content. Since the receiver 50 does not have a decryption functionhowever, sometimes the receiver 50 cannot be used for copying contentwithout inviting degradation of the quality of the image etc., forexample, it does not have the function of outputting the supplieddigital three-primary color image signal or converting the three-primarycolor image signal to for example an NTSC system video signal for outputand therefore cannot display the image of the content even if it isclear that copyright protection is possible.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a transmitter and asignal transfer method enabling correct display of an image even if atransmitter for a digital image signal designed for a digital transfermethod incorporating encryption technology for copyright protection isconnected with a receiver designed for a digital transfer method notincorporating encryption technology for copyright protection.

Another object of the present invention is to provide a datadistribution system and a data distribution method enabling a contentowner to directly control copying as desired while using a standardapparatus as a processor after the receiver.

Still another object of the present invention is to provide a datareceiver used in such a content distribution system, receiving thedistributed content data, performing adequate right processing, andoutputting the content data in a usable manner.

Still another object of the present invention is to provide a dataprovider and a data providing method for providing content data to bedistributed in a state where the owner of the content can control theusage thereof.

Still another object of the present invention is to provide a datatransferer for transferring the data provided in this way.

Accordingly, a transmitter according to the present invention comprisesa transmission processing means for transferring a content signal orprocessing copyright protection to a content signal and thentransferring the processed content signal and a transmission controllingmeans for holding information indicating a receiver which does not havea function enabling copying of content by using the content signal theprocessed content signal transferred from the transmission processingmeans and controlling output of the signal to be transferred from thetransmission processing means according to whether or not informationindicating the receiver which is connected to the transmissionprocessing means is included in the held information.

A signal transfer method according to the present invention includes thesteps of holding in a transmitter information indicating receivers nothaving the function of being able to receive a content signal to copythe content and controlling the output of the content signal or contentsignal after provided with copyright protection at the transmitteraccording to whether or not information indicating a connected receiveris included in the held information.

In the present invention, when for example the model names of receiversnot having the function of being able to use a transferred contentsignal to copy the content are held in a transmitter in advance and themodel name of a connected receiver is included in the held model names,a non-copyright protected content signal is transferred from thetransmitter to the receiver regardless of whether or not the content tobe transferred is copyright protected. Also, when a change of thereceiver is detected by a hot plug detection function or a plug and playfunction while transferring a content signal of copyright protectedcontent without providing copyright protection, the transfer of thenon-copyright protected content signal is suspended or a copyrightprotected content signal is transferred instead of the non-copyrightprotected content signal. Also, the transmitter holds the model name orother information indicating the receiver in a tamper-proof updateablemanner.

A data distribution system according to the present invention comprisesa data providing means for adding first control information forcontrolling a usage state of the content data to the intended contentdata and providing the result as the data to be distributed, a datatransmitting means for performing predetermined second encryption on theprovided data to be distributed and transmitting the encrypted data tobe distributed, and a data receiving means for receiving the transmittedencrypted data to be distributed, performing decryption of the secondencryption, detecting the first control information from the decrypteddata to be distributed, and controlling the output of the content databased on the detected first control information.

Preferably, the data providing means superimposes the first controlinformation as electronic watermark information on the content data andprovides the superimposed content data as the data to be distributed tothe data transmitting means, the data transmitting means performs thepredetermined second encryption on the provided data to be distributedand transmits the encrypted data to be distributed, and the datareceiving means receives the transmitted encrypted data to bedistributed, performs the decryption of the second encryption, detectsthe superimposed first control information from the decrypted data to bedistributed, and controls the output of the content data based on thedetected first control information.

More preferably, the data providing means performs predetermined firstencryption on the content data with the first control informationsuperimposed thereon as the electronic watermark information andprovides the encrypted data as the data to be distributed to the datatransmitting means, the data transmitting means performs the secondencryption for the provided data to be distributed and transmits theencrypted data to be distributed, and the data receiving means receivesthe transmitted encrypted data to be distributed, performs thedecryption of the second encryption, generates the content data with theelectronic watermark information superimposed thereon by performing thedecryption of the first encryption, detects the superimposed firstcontrol information from the generated content data, and controls theoutput of the content data based on the detected information.

Specifically, the data transmitting means adds second controlinformation for controlling a usage state of the content data to theprovided data to be distributed, performs the second encryption on thedata to be distributed with the second control information addedthereto, and transmits the encrypted data to be distributed, the datareceiving means receives the transmitted encrypted data to bedistributed, performs the decryption of the second encryption, detectsthe second control information, generates the content data with theelectronic watermark information superimposed thereon by performing thedecryption of the first encryption for the decrypted data to bedistributed, detects the first control information superimposed as theelectronic watermark information from the generated content data, andcontrols the output of the content data based on the detected firstcontrol information and second control information.

More specifically, the data providing means adds a control descriptorindicating the first control information to the content data andprovides the content data with the control descriptor added thereto asthe data to be distributed to the data transmitting means, the datatransmitting means performs the predetermined second encryption for theprovided data to be distributed and transmits the encrypted data to bedistributed, and the data receiving means receives the transmittedencrypted data to be distributed, performs the decryption of the secondencryption, detects the added first control information from thedecrypted data to be distributed, and controls the output of the contentdata based on the detected first control information.

Preferably, the data transmitting means adds second control informationfor controlling a usage state of the content data to the provided datato be distributed, performs the second encryption for the data to bedistributed with the second control information added thereto, andtransmits the encrypted data to be distributed, and the data receivingmeans receives the transmitted encrypted data to be distributed,performs the decryption of the second encryption, detects the secondinformation, performs the decryption of the first encryption for thedecrypted data to be distributed to generate content data with thecontrol descriptor added thereto, detects the first control informationadded as the control descriptor from the generated content data, andcontrols the output of the content data based on the detected firstcontrol information and second control information.

Preferably, the data providing means superimposes third controlinformation for controlling a usage state of the signal when outputtingthe content data by an analog signal on the content data as theelectronic watermark information and provides the content data with thethird control information superimposed thereon as the data to bedistributed, the data transmitting means performs the predeterminedsecond encryption for the provided data to be distributed, transmits theencrypted data to be distributed, and the data receiving means receivesthe transmitted encrypted data to be distributed, performs thedecryption of the second encryption, and outputs the signal with thedecrypted the third control information superimposed thereon as theelectronic watermark information as the analog signal output in responseto a request.

Preferably, the data receiving means further has a memory means forstoring information concerning charging with respect to a usage of thecontent data based on a usage state of the received content data.

A data distribution method according to the present invention comprisesthe steps of adding first control information for controlling a usagestate of content data to intended content data based on an instructionof an owner of the content data and providing the result as the data tobe distributed, performing predetermined second encryption on theprovided data to be distributed, transmitting the encrypted data to bedistributed, receiving the transmitted encrypted data to be distributedat any receiver, performing the decryption of the second encryption,detecting the first control information from the decrypted data to bedistributed, and controlling the output of the content data based on thedetected first control information.

A data receiver according to the present invention is a data receiverfor receiving a signal comprised of data to be distributed includingintended content data plus first control information for controlling ausage state of the content data and transmitted after performingpredetermined second encryption, comprising a receiving means forreceiving the transmitted signal, a second decrypting means forperforming decryption of the second encryption with respect to thereceived signal, a first control information detecting means fordetecting the first control information from the decrypted data to bedistributed, and an output controlling means for controlling the outputof the content data based on the detected first control information.

A data provider according to the present invention has a controlinformation adding means for adding control information for controllinga usage state of content data designated by an owner of the content datato intended content data and provides the content data with the controlinformation added thereto as data to be distributed.

A data providing method according to the present invention comprises thesteps of adding control information for controlling a usage state ofcontent data designated by an owner of content data to intended contentdata, encrypting the content data with the control information addedthereto by a predetermined method, and providing the encrypted contentdata as the data to be distributed.

A data transferer according to the present invention comprises anencrypting means for further encrypting, by a predetermined method, datato be distributed including intended content data plus controlinformation for controlling a usage state of the content data designatedby an owner of the content data and encrypted by a predetermined schemeand a transferring means for transferring the encrypted data to bedistributed to any channel.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and features of the present invention will become moreapparent from the following description given with reference to theaccompanying drawings, wherein:

FIG. 1 is a conceptual view of a signal transfer system according to thepresent invention,

FIG. 2 is a view of a pin arrangement of a connector of the DVIspecification,

FIG. 3 is a flowchart of an operation of a transmitter,

FIG. 4 is a conceptual view of a signal transfer system of the DVIspecification,

FIG. 5 is a conceptual view of a signal transfer system designed for theDVI-CP specification,

FIG. 6 is a view of compatibility of hardware based on the DVIspecification and hardware based on the DVI-CP specification,

FIG. 7 is a view of an overall schematic configuration of a contentdistribution system of a second embodiment of the present invention,

FIG. 8 is a view of the configuration of a principal part of a firstconcrete example of the content distribution system shown in FIG. 7,

FIG. 9 is a view of the configuration of a principal part of a secondconcrete example of the content distribution system shown in FIG. 7,

FIG. 10 is a view of the configuration of a principal part of a thirdconcrete example of the content distribution system shown in FIG. 7,

FIG. 11 is a flowchart for explaining decision processing in a decisioncontroller of a set top box shown in FIG. 10,

FIG. 12 is a view of the configuration of a principal part of a fourthconcrete example of the content distribution system shown in FIG. 7,

FIG. 13 is a flowchart for explaining the decision processing in thedecision controller of the set top box shown in FIG. 12,

FIG. 14 is a view of the configuration of a principal part of a fifthconcrete example of the content distribution system shown in FIG. 7, and

FIG. 15 is a view of the configuration of a principal part of a sixthconcrete example of the content distribution system shown in FIG. 7.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will be explained nextreferring to the attached drawings.

First Embodiment

Below, an explanation will be made of a first embodiment of the presentinvention by referring to the drawings.

FIG. 1 is a conceptual view of a signal transfer system for transferringa digital image signal of content. A transmitter (for example a computersystem or set top box) 10 for transmitting the image signal and areceiver (display device, television set, etc.) 40 for receiving theimage signal and displaying the image are connected via DVIspecification channels 30. The DVI specification channels 30 areprovided with a TMDS channel for transferring the digital image signal,a bi-directional channel used for DDC (display data channel)specification information transfer relating to plug and play establishedby the VESA (Video Electronics Standard Association), a power supplyline, and a hot plug detection use signal line.

FIG. 2 is a view of a pin arrangement of a DVI specification connector.Note that the figure shows the case where a channel for transferring ananalog image signal is provided. Pins “1” to “5”, “9” to “13”, and “17”to “24” are for TMDS channels, pins “6” and “7” are for DDC usebi-directional channels (I²C bus), and pins “C1” to “C5” are forchannels for analog image signals. Further, pins “14” and “15” are for a5V power supply line and a ground line, and a pin “16” is defined as fora hot plug detection use signal line.

An image signal generator 11 of the transmitter 10 shown in FIG. 1generates a three-primary color image signal DG of the content by aresolution and number of colors optimum with respect to the receiver 40based on a signal generation control signal GC supplied from a DDCprotocol processing circuit 152 mentioned later and supplies the same toan encryption circuit 121 of a transmission processor 12, a terminal aof a signal selection circuit 122, and a protection information detector13.

The encryption circuit 121 of the transmission processor 12 encrypts thethree-primary color image signal DG by for example an encryption key KCand supplies it as the three-primary color image signal DGE to aterminal b of the signal selection circuit 122. A moveable terminal c ofthe signal selection circuit 122 is connected to one terminal of theoutput control switch 123, is controlled by a protection operationcontrol signal PT supplied from a authentication processing circuit 151of a transmission controller 15 mentioned later, and selects either ofthe non-encrypted three-primary color image signal DG supplied to theterminal a or the encrypted three-primary color image signal DGEsupplied to the terminal b.

The other terminal of the output control switch 123 is connected to aTMDS transmission circuit 124. The on/off operation of this outputcontrol switch 123 is also controlled by a protection operation controlsignal PU from the authentication processing circuit 151.

The TMDS transmission circuit 124 encodes the three-primary color imagesignal selected at the signal selection circuit 122 and supplied via theoutput control switch 123, tries to balance a DC level and minimize thenumber of times of inversion of the logic level, and converts the signalto a baseband serial transfer signal SD suitable for transfer. Theserial transfer signal SD for each color is output from a connector 17to a channel 30. Note that a horizontal synchronization signal and avertical synchronization signal of the three-primary color image signalDG are inserted in a blanking period of for example a blue image signaland transmitted.

The protection information detector 13 detects whether to providecopyright protection according to the copyright protection informationof the three-primary color image signal DG and supplies a decisionsignal PD to the authentication processing circuit 151. As thiscopyright protection information, use is made of CGMS (copy generationmanagement system) information indicating if the content can be freelycopied or copying is prohibited or whether to recognize only one copy orCCI (copy control information) etc. Also, when an analog image signal issupplied to the image signal generator 11 and this analog image signalis transferred converted to a digital signal, it is also possible todecide whether or not to provide copy protection based on an APS (analogprotection system) signal for copyright protection used in the analogimage signal.

The authentication processing circuit 151 of the transmission controller15 is comprised using an electrically programmable nonvolatile memory.This authentication processing circuit 151 registers in itclassification information of receivers to be connected to thetransmitter 10, for example, the model names of the receivers. As theclassification information registered in this authentication processingcircuit 151, classification information indicating the receivers nothaving a function for copying the content without inviting degradationof the quality of image etc., for example, classification informationindicating the receivers not having a function for outputting thesupplied digital image signal or converting the digital image signal tofor example an NTSC system video signal and outputting the same isregistered. Also, the authentication processing circuit 151 decideswhether or not the model name of the receiver indicated by hardwareinformation RR supplied from the DDC protocol processing circuit 152mentioned later is registered and generates the protection operationcontrol signals PT and PU and supplies them to the transmissionprocessor 12 based on this decision result and the decision signal PDsupplied from the protection information detector 13.

The DDC protocol processing circuit 152 communicates with the receiver40 via the connector 17 and the channels 30 in accordance with the DDCprotocol and supplies the hardware information RR supplied from thereceiver 40 to the authentication processing circuit 151. Also, the DDCprotocol processing circuit 152 performs the authentication processingwith the connected receiver 40 based on the decision result at theprotection information detector 13 so as to decide whether or not theconnected receiver 40 is based on the new specification including theencryption technology for copyright protection. Here, when it isconfirmed that the receiver 40 is based on the new specification, thecircuit performs processing for supplying the encryption key KC usedwhen encrypting the three-primary color image signal DG to the receiver40. Note that the encryption key KC may be held in the DDC protocolprocessing circuit 152, may be supplied from the DDC protocol processingcircuit 152 to the encryption circuit 121, or may be read out by the DDCprotocol processing circuit 152 from the encryption circuit 121 whensupplying the encryption key KC to the receiver 40.

Further, the DDC protocol processing circuit 152 generates the transfercontrol signal TC and supplies the same to the TMDS transmission circuit124 so as to control the generation and transfer processing of thebaseband serial transfer signals SD performed at the TMDS transmissioncircuit 124.

A connector 41 of the receiver 40 has a reception processor 42 and areception controller 43 connected to it. The reception processor 42generates the three-primary color image signal DS based on receivedserial transfer signal SD and supplies it to a display 44. When adecryption circuit for decrypting the encrypted three-primary colorimage signal is provided in the reception processor 42 and theencryption key KC transferred from the transmitter 10 is supplied fromthe reception controller 43, the circuit performs the decryptionprocessing of the encrypted three-primary color image signal using thisencryption key KC.

Next, an explanation will be made of the operation of the transmitter 10by using the flowchart of FIG. 3. At step ST1, the transmittercommunicates with the connected receiver 40 to obtain the model name,resolution, or other hardware information relating to the receiver 40and generates a signal generation control signal GC based on thishardware information for supply to the image signal generator 11.

At step ST2, it is decided based on the decision signal PD whether ornot the content supplied from the transmitter 10 to the receiver 40 iscopyright protected. Here, when it is decided based on the decisionsignal PD from the protection information detector 13 that the contentis not copyright protected, the routine proceeds to step ST3, where themoveable terminal c of the signal selection circuit 122 is set to theterminal a side by the protection operation control signal PT and theunencrypted three-primary color signal DG is selected, then the routineproceeds to step ST9.

Also, when it is decided at step ST2 that the content is copyrightprotected, the routine proceeds to step ST4, where the authenticationprocessing with the receiver 40 is carried out, and it is decidedwhether or not the connected receiver 40 is based the new specificationincluding the encryption technology for copyright protection. Thisauthentication processing assumes that for example a common key methodis utilized, sends the data from the transmitter 10 to the receiver 40,and encrypts and returns the data by the common key held at the receiver40. If this returned encrypted data is inversely converted by the commonkey and it can be confirmed that the transmitted data appears, it can becorrectly decided that the receiver is based on the new specification.Also, if a public key system is utilized, the data is encrypted by thepublic key of the receiver 40 and sent from the transmitter 10, the datadecrypted by a secret key is returned from the receiver 40, and it canbe confirmed that this returned data is equal to the data which wasencrypted and transmitted, it can be correctly decided that the receiveris based on the new specification.

When it is decided at step ST4 that the receiver 40 is based on the newspecification, the routine proceeds to step ST5, where the encryptionkey KC used at the encryption circuit 121 is supplied from the DDCprotocol processing circuit 152 to the reception controller 43, then theroutine proceeds to step ST6.

At step ST6, the moveable terminal c of the signal selection circuit 122is set to the terminal b side by the protection operation control signalPT so as to select the encrypted three-primary color image signal DGE,then the routine proceeds to step ST9.

When it is not decided at step ST4 that the receiver 40 is based on thenew specification, the routine proceeds to step ST7, where it is decidedwhether or not the model name of the receiver 40 indicated by thehardware information RR supplied from the DDC protocol processingcircuit 152 is registered in the authentication processing circuit 151.Here, when it is decided that the model name of the receiver isregistered and the receiver does not have a function enabling it to copycontent without inviting degradation of the quality of image etc., theroutine proceeds to step ST8. Also, when it is not registered, theroutine proceeds to step ST10.

At step ST8, the moveable terminal c of the signal selection circuit 122is set to the terminal a side by the protection operation control signalPT so as to select the unencrypted three-primary color image signal DG,then the routine proceeds to step ST9.

When the routine proceeds from step ST3 or step ST6 or step ST8 to stepST9, the output control switch 123 is turned on by the protectionoperation control signal PU to generate the serial transfer signal SDbased on the unencrypted three-primary color image signal DG or theencrypted three-primary color image signal DGE selected at the signalselection circuit 122 and transmit it to the receiver 40. Also, when theroutine proceeds from step ST7 to step ST10, at step ST10, the outputcontrol switch 123 is turned off by the protection operation controlsignal PU and the transfer of the serial transfer signal SD based on thethree-primary color image signal DG or DGE is prohibited.

When copyright protection of the content to be transferred is necessaryin this way, when a receiver based on the new specification includingencryption technology for copyright protection is connected, the contentis transmitted encrypted, so illicit copying of the content can beprevented. Also, even if a receiver 40 not based on the newspecification is connected, when it is confirmed that this connectedreceiver is hardware not having a function of copying the content, thecontent is transmitted without being encrypted, therefore not only canillicit copying of the content be prevented, but also even a receivernot based on the new specification can be made to correctly display theimage of the content.

Further, while a digital image signal of content requiring encryption isbeing transmitted without encryption, it is monitored whether or notthere has been a change of connection of the receiver, that is, if thereceiver 40 connected to the transmitter 10 has been disconnected or thereceiver 40 has been changed. A change of connection of the receiver ismonitored by utilizing for example the hot plug detection function orplug and play function. Here, if the hot plug detection function isutilized, it can be decided whether or not the connection of thereceiver was changed according to whether or not the receiver wasdisconnected by the hot plug detection use signal line. Also, if theplug and play function is utilized, it is possible to perform theprocessing for confirmation of the receiver by the plug and playfunction even during the transfer of the image signal and thereforedecide whether or not there has been a change in connection of thereceiver during the transfer of the image signal.

When it is decided that there has not been a change in connection duringthis monitoring of a change of connection of the receiver, the outputcontrol switch 123 is held in the on state by the protection operationcontrol signal PU, while when it is decided that there has been a changein connection, the signal selection circuit 122 and the output controlswitch 123 are controlled by the protection operation control signals PTand PU so that the unencrypted three-primary color image signal DG isnot transmitted. For example, by turning the output control switch 123off by the protection operation control signal PU, the transfer of theunencrypted three-primary color image signal DG can be stopped. Also, byswitching the moveable terminal c of the signal selection circuit 122 tothe terminal b side by the protection operation control signal PT andselecting the encrypted three-primary color image signal DGE, theunencrypted three-primary color image signal DG can be prevented frombeing transferred.

In this way, even when there is a change in the connection of thereceiver while the image signal of the content is being transferredwithout encryption and, for example, a receiver having a function forcopying content without inviting degradation of the quality of imageetc. is connected, the unencrypted three-primary color image signal DGis no longer automatically transferred, so the illicit copying of thecontent can be prevented.

The authentication processing circuit 151 is configured using aprogrammable nonvolatile memory, so new model names can be added to theauthentication processing circuit 151. Here, if the informationregistered in the authentication processing circuit 151 were tamperedwith and the model name of a receiver having a function for copying thecontent without inviting degradation of the quality of image etc. wereregistered, the content could be illicitly copied.

For this reason, the authentication processing circuit 151 uses a meanshaving a high safety so as to prevent the stored information from beingtampered with. For example, the hardware is configured so that theinformation is lost at the time of reverse engineering of theauthentication processing circuit 151 or the circuit is configured tomake analysis of the information difficult. Also, when updating thestored information, in the same way as the above authenticationprocessing, it is decided whether or not the hardware connected to thetransmitter for updating the stored information is correct by utilizingthe common key system or the public key system and the update of thestored information is permitted only when it is decided that theapparatus is correct. Further, when the transmitter is hardware such asa set top box, it is also possible to encrypt the information to beupdated and supply it to the set top box from the broadcast station sideby using the information transmission use channel and have the set topbox decrypt the encrypted information by using he secret key stored inan IC card or the like unique to the viewer and update the storedinformation by using the decrypted information. Also, the transmitter isa computer system.

Note that, in the first embodiment, whether or not the content iscopyright protected is determined by using a three-primary color imagesignal DG, but even if information on whether or not the three-primarycolor image signal DG must be processed for copyright protection issupplied by the image signal generator 11 to the transmission controller15, it is possible to similarly operate the transmitter 10. Further, thesignal of the content to be transferred is not limited to an imagesignal and of course may also be a voice signal.

In this way, according to the first embodiment, even if a receiver notbased on this new specification is connected to a transmitter based onthe new specification including the encryption technology for copyrightprotection, it is possible to register this receiver not based on thenew specification in the transmitter so as to enable a signal outputfrom a transmitter based on the new specification to be received at thereceiver not based on the new specification and the content to be used.

Second Embodiment

Next, the content distribution system and content distribution methodenabling a content owner to directly control copying as desired whileusing a standard apparatus as the processing apparatus after thereceiver will be explained as a second embodiment of the presentinvention by referring to FIG. 13 to FIG. 15.

Overall Configuration

First, an overall configuration of the content distribution system ofthe second embodiment will be explained by referring to FIG. 7.

FIG. 7 is a view of the overall schematic configuration of a contentdistribution system 1100 of the second embodiment.

The content distribution system 1100 has a content owner 1200,broadcaster 1300, broadcast network 1400, set top box 1500, displaydevice I/F 1600, and display device 1700.

First, the configuration of each part will be explained.

The content owner 1200 is the owner of the content to be distributed,encrypts the content to be distributed by using a desired encryption keyKa, and provides the content in the encrypted state to the broadcaster1300. In the present embodiment, the “content” means content includingimages and sound, for example, TV programs or movies.

Note that the “encryption” referred to here broadly means processing thecontent data itself or any additional data or the like desired by thecontent owner 1200 to a state preventing it from being changed in anyway, read, or used. Accordingly, it specifically includes superimposingadditional data in the form of an electronic watermark etc. whenactually encrypting content data. Note that, the actual concreteprocessing content will be explained at the later more concreteexplanation of the configuration.

The broadcaster 1300 further performs encryption for conditional accessby using an encryption key Kb on the content in the encrypted stateprovided by the content owner 1200 and distributes the same via thebroadcast network 1400.

The broadcast network 1400 is any data distributing means including anydata distribution system via the communication network going through acommunication network such as a digital ground wave broadcast, digitalsatellite broadcast, CATV, or the Internet and distributes the contentdata transferred by the broadcaster 1300 to any user.

The set top box 1500 is a receiver provided in for example the home ofeach user and receiving the data transferred by the broadcaster 1300 viathe broadcast network 1400 based on an operation of the user.

The set top box 1500 decrypts the content data by using the encryptionkey Ka delivered based on for example a contract in advance whenreceiving the content data selected by the user. Then, it encrypts thedecrypted content data again by using the encryption key Kc set inadvance and transfers it to the display device I/F 1600. In the presentembodiment, the set top box 1500 and the display device 1700 areconnected using IEEE1394 as the interface, then the set top box 1500encrypts the content data again by the 5C encryption scheme defined inthe IEEE1394.

The display device I/F 1600 is a connecting means between the set topbox 1500 and the display device 1700 and is the IEEE1394 in the presentembodiment as mentioned before.

The display device 1700 decrypts the encrypted content data input fromthe set top box 1500 via the display device I/F 1600 by using theencryption key Kc set in advance and displays the same in auser-viewable manner.

Next, the basic overall operation of the content distribution system1100 having such a configuration will be explained.

First, the content to be distributed is encrypted by the owner, that is,the content owner 1200, by using the encryption key Ka, then transferredto the broadcaster 1300, then is further encrypted for conditionalaccess by the broadcaster 1300 by using the encryption key Kb andtransferred to the broadcast network 1400.

The data transferred to the broadcast network 1400 is specificallysubstantially received by the viewer (user of the content) selected tobe viewed from the set top box 1500 operated by the user and theencryption for the conditional access is first decrypted by an internaldecryptor. The encryption key Ka at this time is provided in the form ofa secure storage medium such as an IC card when the user concludes areception contract with the broadcaster 1300 in advance.

The decrypted content data is encrypted again by the 5C scheme of theIEEE1394 by using the encryption key Kc set in advance and istransferred to the display device 1700.

Then, it is decrypted at the display device 1700 and displayed in a userviewable manner.

Note that the operation performed by the viewer on the set top box 1500such as the selection of the content data to be received and thetransfer of the content data from the set top box 1500 to the displaydevice 1700 is successively stored in the charge information memory inthe set top box 1500 and used for the charging accompanying thereception of content.

In this way, in the content distribution system 1100, the content owner1200 itself substantially encrypts the content to be distributed. Theencryption is not decrypted until the set top box 1500 of the user.Accordingly, if the control information for controlling for example thereproduction or copying of the content data on the user side isencrypted and superimposed on the content data, the content owner 1200itself can control the usage of the content data on the user side.Namely, a change of the usage state, usage conditions, etc. of thecontent set by the broadcaster 1300 can be prevented regardless of thereason.

Also, in the content distribution system 1100, a standard interface canbe used between the set top box 1500 and the display device 1700 whileplacing the usage of the content within a range of such control of thecontent owner 1200. Also, the standard hardware compatible with thatinterface can be used as the display device 1700.

EXAMPLE OF CONCRETE APPLICATION

The basic overall configuration of the content distribution system 1100according to the present invention was explained above, but an exampleof a more concrete configuration and concrete form of application willbe explained as a first concrete example to fifth concrete example.

Note that all of the broadcast network 1400, display device I/F 1600,and display device 1700 are standard, therefore, in the followingexplanation, the illustration of these in the drawings and explanationsthereof will be omitted.

First Concrete Example

A first example of concrete application of the content distributionsystem 1100 will be explained by referring to FIG. 8.

As the first concrete example, a system wherein the content owner 1200superimposes the control information for controlling the usage of thecontent on the content data in the form of an electronic watermark anddistributes the same and wherein the usage of the content data receivedby the user is controlled by this will be illustrated.

FIG. 8 is a view of the configuration of the content owner 1200 to theset top box 1500 of the first concrete configuration of the contentdistribution system 1100.

In the first concrete configuration shown in FIG. 8, the content owner1200 has an electronic watermark superimposer 1208 which superimposesthe copy control information for controlling the usage of the contentwhich becomes valid in the set top box 1500 on the content data in theform of an electronic watermark.

Further, the content owner 1200 has an encryptor 1210 which encrypts thecontent data with the electronic watermark superimposed thereon by usingthe encryption key Ka.

Then, it transfers this encrypted content data to the broadcaster 1300.

The broadcaster 1300 has the encryptor 1302 which further performsencryption for conditional access by using the encryption key Kb on thecontent data input from the content owner 1200 and transmits the same.

The set top box 1500 has a decryptor 1502, decryptor 1504, electronicwatermark detector 1506, 5C encryptor 1508, output switch 1510, andcharge information memory 1524.

The decryptor 1502 decrypts the encrypted signal received from thebroadcaster 1300 by using the encryption key Kb. Namely, it decrypts theencryption for the conditional access. The decrypted signal is thesignal encrypted by the content owner 1200 and can not yet used.

The decryptor 1504 further decrypts the signal decrypted at thedecryptor 1502 by using the encryption key Ka and outputs the decryptedsignal to the electronic watermark detector 1506, 5C encryptor 1508, andthe output switch 1510. The signal decrypted at the decryptor 1504 isthe signal obtained by the superimposition of the copy controlinformation on the baseband content data as the electronic watermark.

The electronic watermark detector 1506 detects the copy controlinformation superimposed as the electronic watermark from the signaldecrypted at the decryptor 1504, generates the signal for controllingthe signal to be output from the set top box 1500, concretely the signalfor controlling the output switch 1510 based on this, and applies thesame to the output switch 1510.

The 5C encryptor 1508 encrypts the signal decrypted at the decryptor1504 by the 5C scheme by using the encryption key Kc and applies thesame to the output switch 1510.

The output switch 1510 selects either of the unencrypted content dataoutput from the decryptor 1504 or the content data encrypted at the 5Cencryptor 1508 as the output signal from the set top box 1500 based onthe control signal applied from the electronic watermark detector 1506and outputs the same from the set top box 1500.

The charge information memory 1524 detects and stores the informationrelating to the charge accompanying the usage of the content data bydetecting the signal substantially output from the set top box 1500 ormonitoring the information input from the display device 1700 via theIEEE1394. The information stored in the charge information memory 1524is suitably transmitted to a predetermined settlement manager where thecharge processing is performed.

In such a set top box 1500, the encryption for the conditional accessapplied at the decryptor 1502 by the broadcaster 1300 is decrypted, theencryption applied by the content owner 1200 itself is decrypted at thedecryptor 1504, and the copy control information added by the contentowner 1200 superimposed as the electronic watermark is detected at theelectronic watermark detector 1506 from that decrypted content data.

Then, when for example this copy control information describes to outputthe encrypted content data from the set top box 1500, the data obtainedby encrypting the output from the decryptor 1504 at the 5C encryptor1508 using the encryption key Kc is selected by the output switch 1510based on the control signal from the electronic watermark detector 1506and output from the set top box 1500 to a not illustrated displaydevice.

Also, when the copy control information describes that unencryptedcontent data can be output from the set top box 1500, the output fromthe decryptor 1504 is selected by the output switch 1510 based on thecontrol signal from the electronic watermark detector 1506 and outputfrom the set top box 1500.

In this way, in the first concrete example, the content owner 1200superimposes the copy control information on the content data in theform of the electronic watermark and further performs encryption. Thecontent owner 1200 itself can directly control the output of thereception side without intervention by the broadcaster 1300.

Second Concrete Example

A second example of concrete application of the content distributionsystem 1100 will be explained next by referring to FIG. 9.

The second concrete example is configured as the first concrete examplewithout the encryptor 1210 of the content owner 1200 and omitting theencryption processing. Also, along with this, the set top box 1500 isalso configured omitting the decryptor 1504.

In such a configuration, the content owner 1200 superimposes the copycontrol information in the form of an electronic watermark at theelectronic watermark superimposing unit 1208 and provides the contentdata in that state to the broadcaster 1300 as it is, that is, withoutencryption.

Then, the broadcaster 1300 performs the encryption for the conditionalaccess on this at the encryptor 1302 and transfers the result.

The set top box 1500 receiving the transferred signal decrypts theencryption for conditional access at the decryptor 1502 to directlyobtain content data not encrypted in any way, detects the copy controlinformation superimposed as the electronic watermark at the electronicwatermark detector 1506, and controls the output switch 1510 by this.

The operations of the 5C encryptor 1508, output switch 1510, notillustrated charge information memory, etc. are the same as those of thefirst concrete example.

In this way, the second concrete example omits the encryptor 1210 in thecontent owner 1200 and the decryptor 1504 of the set top box 1500, socan simplify the configurations of the devices.

In such a configuration, the encryption processing by the encryptor 1210of the content owner 1200 is eliminated, therefore the content data inthe unencrypted state is transferred to the broadcaster 1300. The outputof the set top box 1500, however, is controlled by the electronicwatermark information. Further, the electronic watermark data issuperimposed. Therefore, illicit usage can be traced, so the possibilityof illicit usage can be said to be low.

If such a condition is acceptable, this simple configuration secondconcrete example is effective.

Third Concrete Example

An explanation will be made of a third concrete application example ofthe content distribution system 1100 by referring to FIG. 10 and FIG.11.

The third concrete example is configured by the broadcaster 1300 addinga unique control descriptor separate from that added by the contentowner 1200.

Specifically, the processing in the content owner 1200 is the same asthe processing of the first concrete example. First the copy controlinformation for controlling the usage of the content which becomes validin the set top box 1500 is superimposed on the content data in the formof an electronic watermark. Next, the encryptor 1210 encrypts thecontent data with the electronic watermark superimposed thereon by usingthe encryption key Ka and transfers this encrypted content data to thebroadcaster 1300.

The broadcaster 1300 adds the unique control descriptor to the encryptedcontent data transferred from the content owner 1200 in a controldescriptor adder 1306, encrypts this in the encryptor 1302 by using theencryption key Kb, and transmits the same.

The set top box 1500 receiving this decrypts the encryption for theconditional access performed by the broadcaster 1300 in the decryptor1502 by using the encryption key Kb.

From this decrypted signal, the control descriptor added by thebroadcaster 1300 is detected at the control descriptor detector 1512 andoutput to a decision controller 1514.

Also, the signal decrypted at the decryptor 1502 is further decrypted atthe decryptor 1504 by using the encryption key Ka.

The electronic watermark detector 1506 detects the copy controlinformation superimposed in the form of an electronic watermark by thecontent owner 1200 from this decrypted signal and outputs it to thedecision controller 1514.

The decision controller 1514 performs the decision for controlling theusage of the received content data based on the copy control informationset by the content owner 1200 and input from the electronic watermarkdetector 1506 and the control descriptor set by the broadcaster 1300 andinput from the control descriptor detector 1512 and controls the outputdata based on that decision.

Here, it is assumed that the copy control information and the controldescriptor set to output the content data from each set top box 1500 byeither transfer by 5C encryption or by transfer without encryption. Inthat case, the decision controller 1514 performs a decision according tothe flowchart as shown in for example FIG. 11.

Namely, when the decision is started (step S10), first, the copy controlinformation input from the electronic watermark detector 1506 isreferred to so as to judge whether it sets 5C encryption (step S11).When it sets 5C encryption, a control signal for selecting the output ofthe 5C encryptor 1508 is output to the output switch 1510, whereby 5Cencrypted content data is output from the set top box 1500 (step S12).

When the copy control information input from the electronic watermarkdetector 1506 does not set 5C encryption (step S11), the controldescriptor input from the control descriptor detector 1512 is referredto so as to judge whether or not it sets 5C encryption (step S13). Then,when it sets 5C encryption, in the same way as the case where the copycontrol information sets it, a control signal for selecting the outputof the 5C encryptor 1508 is output to the output switch 1510, whereby 5Cencrypted content data is output from the set top box 1500 (step S12).

Even when the control descriptor input from the control descriptordetector 1512 does not set 5C encryption (step S13), the decisioncontroller 1514 outputs a control signal for selecting the output fromthe decryptor 1504 to the output switch 1510 to make the set top box1500 output the unencrypted content data (step S14).

In this way, the third concrete example enables the content owner 1200and the broadcaster 1300 to independently set control of the usage ofthe content data. Then, it is possible to freely set which settingshould be given priority and what kind of control is to be carried outby changing an algorithm set in the decision controller 1514.

BAy employing the algorithm as shown in for example FIG. 11, it ispossible to execute the setting of the content owner 1200 with priorityover the setting of the broadcaster 1300.

Fourth Concrete Example

Next, a fourth example of concrete application of the contentdistribution system 1100 will be explained by referring to FIG. 12 andFIG. 13.

The fourth concrete example is configured similar to the third concreteexample, but the copying is controlled by the content owner 1200 not bysuperimposing an electronic watermark on the content data, but by addinga control descriptor to the content data in the same way as thebroadcaster 1300.

Namely, the content owner 1200 adds copy control information forcontrolling the usage of the content which becomes valid in the set topbox 1500 to the content data in the form of a control descriptor(control descriptor 1) by a control descriptor adder 1212. Then, thecontent data with the control descriptor added thereto is encrypted atthe encryptor 1210 by using the encryption key Ka and the encryptedcontent data is transferred to the broadcaster 1300.

The broadcaster 1300 adds a unique control descriptor (controldescriptor 2) to the encrypted content data transferred from the contentowner 1200 at the control descriptor adder 1306, encrypts this at theencryptor 1302 by using the encryption key Kb, and transfers the same.

The set top box 1500 receiving this decrypts the encryption for theconditional access performed by the broadcaster 1300 at the decryptor1502 by using the encryption key Kb. A control descriptor 2 detector1512 detects the control descriptor 2 added by the broadcaster 1300 fromthis decrypted signal and outputs the result to the decision controller1514.

The signal decrypted at the decryptor 1502 is further decrypted at thedecryptor 1504 by using the encryption key Ka. Then, a controldescriptor 1 detector 1516 detects the control descriptor 1 added by thecontent owner 1200 from this decrypted signal and outputs it to thedecision controller 1514.

The decision controller 1514 performs the decision for controlling theusage of the received content data based on the control descriptor 1 setby the content owner 1200 input from the control descriptor 1 detector1516 and the control descriptor 2 set by the broadcaster 1300 input fromthe control descriptor 2 detector 1512 and controls the output databased on that decision.

Here, it is assumed that the control descriptor 1 and the controldescriptor 2 set to output the content data from each set top box 1500by either transfer by 5C encryption or by transfer without encryption.In that case, the decision controller 1514 performs a decision accordingto the flowchart as shown in for example FIG. 13.

Namely, when the decision is started (step S20), first, the controldescriptor 1 input from the control descriptor 1 detector 1516 isreferred to so as to judge whether it sets 5C encryption (step S21).When it sets 5C encryption, a control signal for selecting the output ofthe 5C encryptor 1508 is output to the output switch 1510, whereby 5Cencrypted content data is output from the set top box 1500 (step S22).

When the control descriptor 1 input from the control descriptor 1detector 1516 does not set 5C encryption (step S21), the controldescriptor 2 input from the control descriptor 2 detector 1512 isreferred to so as to judge whether or not it sets 5C encryption (stepS23). Then, when it sets 5C encryption, in the same way as the casewhere the control descriptor 1 sets this, a control signal for selectingthe output of the 5C encryptor 1508 is output to the output switch 1510,whereby 5C encrypted content data is output from the set top box 1500(step S22).

When the control descriptor 2 input from the control descriptor 2detector 1512 also does not set 5C encryption (step S23), the decisioncontroller 1514 outputs a control signal for selecting the output fromthe decryptor 1504 to the output switch 1510, whereby unencryptedcontent data is output from the set top box 1500 (step S24).

In this way, in the fourth concrete example, the content owner 1200 andthe broadcaster 1300 can independently set control of the usage of thecontent data in the form of adding a control descriptor. Further, theycan freely set how to give priority to what setting and how to controlthe same by changing an algorithm set in the decision controller 1514.

Further, by employing the algorithm as shown in for example FIG. 13, itis possible to execute the setting of the content owner 1200 withpriority over the setting of the broadcaster 1300.

Fifth Concrete Example

A fifth example of concrete application of the content distributionsystem 1100 will be explained next by referring to FIG. 14.

The fifth concrete example enables suitable control of copying even withrespect to analog output from the set top box 1500.

In this case, first, the content owner 1200 superimposes the copycontrol information desired to be set on the content data in the form ofan electronic watermark by the electronic watermark superimposer 1208.This electronic watermark information is used for the copy protection ofthe analog output from the set top box 1500.

Further, the content owner 1200 encrypts the content data with theelectronic watermark information superimposed thereon at the encryptor1210 by using the encryption key Ka. The content owner 1200 transfersboth this encrypted content data and the previous copy controlinformation to the broadcaster 1300.

The broadcaster 1300 converts the copy control information transferredfrom the content owner 1200 to the control descriptor, then adds this tothe encrypted content data transferred from the content owner 1200 atthe control descriptor adder 1306, encrypts the same at the encryptor1302 by using the encryption key Kb, and transfers the same.

The set top box 1500 receiving this decrypts the encryption for theconditional access performed by the broadcaster 1300 at the decryptor1502 by using the encryption key Kb. The control descriptor detector1512 detects the control descriptor added by the broadcaster 1300 fromthis decrypted signal upon instruction from the content owner 1200 andgenerates a control signal for controlling the output switch 1510 andapplies it to the output switch 1510.

Further, the signal decrypted at the decryptor 1502 is further decryptedat the decryptor 1504 by using the encryption key Ka. This decryptedsignal is 5C encrypted at the 5C encryptor 1508 or directly applied tothe output switch 1510. Either is selected at the output switch 1510 andoutput as the digital output.

On the other hand, the signal decrypted at the decryptor 1502 is inputto an analog signal encoder 1518, converted to an analog signal here,and output from the set top box 1500.

In this way, in the fifth concrete example, particularly, it is possibleto output from the set top box 1500 an adequately right processed analogsignal with the copyright protection information superimposed thereon bythe electronic watermark. Accordingly, this is preferred where an analogsignal output is required.

Note that, in the configuration shown in FIG. 14, the copy controlinformation requested by the content owner 1200 is converted to acontrol descriptor by the broadcaster 1300 and added to the contentdata. If the broadcaster 1300 is a sufficiently reliable institution,there is no problem in employing such a configuration. However, when thecontent owner 1200 sets control itself for a certain reason, in the sameway as the case of the third concrete example, the control descriptormay also be set by the content owner 1200.

Sixth Concrete Example

An explanation will be made of a sixth example of concrete applicationof the content distribution system 1100 by referring to FIG. 15.

In the sixth concrete example, the digital output from the set top box1500 is made either of monitor connection use DVI (digital visualinterface) and copyright protected output (DVI-CP) and enable the analogoutput to be turned ON/OFF.

In this case, the content owner 1200 superimposes the copy controlinformation desired to be set on the content data in the form of anelectronic watermark at the electronic watermark superimposing unit1208, encrypts the content data with that electronic watermarkinformation superimposed thereon at the encryptor 1210 by using theencryption key Ka, and transfers the encrypted content data to thebroadcaster 1300.

The broadcaster 1300 adds the unique control descriptor to the encryptedcontent data transferred from the content owner 1200 at the controldescriptor adder 1306, then performs the encryption for the conditionalaccess at the encryptor 1302 by using the encryption key Kb andtransfers the same.

The set top box 1500 receiving this decrypts the encryption for theconditional access performed by the broadcaster 1300 at the decryptor1502 by using the encryption key Kb, detects the control descriptoradded by the broadcaster 1300 from this decrypted signal at the controldescriptor detector 1512, and outputs the same to the decisioncontroller 1514.

Also, the signal decrypted at the decryptor 1502 is further decrypted atthe decryptor 1504 by using the encryption key Ka, and the copy controlinformation superimposed in the form of the electronic watermark by thecontent owner 1200 is detected from this decrypted signal at theelectronic watermark detector 1506 and output to the decision controller1514.

The decision controller 1514 performs the decision for controlling theusage of the received content data based on the copy control informationset by the content owner 1200 input from the electronic watermarkdetector 1506 and the control descriptor set by the broadcaster 1300input from the control descriptor detector 1512 and controls the outputdata based on the decision.

Concretely, the decision controller 1514 performs a decision as towhether to output the baseband data or output data encrypted by theDVI-CP as the digital output from the set top box 1500, makes a decisionas to whether or not to output an analog signal, and outputs controlsignals based on the results of the decision to the output switch 1510and an analog output switch 1522.

Further, the signal decrypted at the decryptor 1504 is encrypted toDVI-CP at an encryptor 1520 or directly applied to the output switch1510. Either is selected at the output switch 1510 and output as thedigital output.

On the other hand, the signal decrypted at the decryptor 1504 is inputto the analog signal encoder 1518, converted to an analog signal here,applied to the analog output switch 1522, selected at the analog outputswitch 1522 under the control of the decision controller 1514, andoutput as the analog output.

In this way, in the sixth concrete example, a digital video signal canbe output from the set top box 1500 by DVI as the RGB baseband signal oran encoded signal. Also, a suitably right processed analog signal withthe copyright protection information superimposed thereon by theelectronic watermark can be selectively output.

Modification

Note that the present invention is not limited to the above embodiments.Various preferred modifications are possible.

For example, the apparatus connected to the set top box 1500 and used inthe content distribution system 1100 was a display device for displayinga video signal, but the invention is not limited to this. Any imageprocessing device can be connected too. For example, it is also possibleto connect a recording device for recording the output data or connect atransfer device for transferring the output data.

Further, the output I/F of the set top box 1500 is not limited to theIEEE1394 and DVI shown in the above embodiments. Any I/F can be used.

Further, the means for transmitting the data between the broadcaster1300 and the set top box 1500 is not limited to a broadcasting means.Any information transmitting means can be applied.

Further, not limited to a so-called broadcast, a transferring means fortransmitting the desired content data to a requesting set top box 1500in response to a request from the set top box 1500 can be used too.

Further, in the present embodiment, the content to be distributed was avideo signal and a video signal containing an audio signal, but it isnot limited to this. It can be applied to the distribution of anycontent data. For example, it can be used as a distribution system ofaudio data, still image data, game software programs, any programsoftware, etc.

As explained above, in the present invention illustrated in the firstand second embodiments, information indicating a receiver not having afunction enabling copying of content indicated by the content signal isheld by utilizing the transferred content signal. When informationindicating the connected receiver is included in this held information,the non-copyright protected content signal is transmitted. For thisreason, a signal compatible with the receiver can be transmitted inaccordance with whether or not the receiver has a function enablingcopying of the content.

Further, when it is decided that the content is copyright protected, acopyright protected content signal is transferred. When it is decidedthat information indicating the connected receiver is included in theheld information, a non-copyright protected content signal istransferred regardless of whether the content is copyright protected.For this reason, so far as the receiver does not have a function forenabling copying, even copyright protected content can be used.

Further, a change in connection of the connected receiver is monitoredfor while transferring a content signal of copyright protected contentdata without providing copyright protection. When a change in connectionis detected, transmission of a non-copyright protected content signal isprohibited. For this reason, even if a receiver having a function forenabling copying is switched to while content signal is beingtransmitted without providing copyright protection, the content can becopyright protected.

Further, since the information indicating the receiver is held in atamper-proof updateable manner, copyright protection can be correctlyprovided to the content. Further, even if a new receiver not having afunction enabling copying is connected, it can be easily handled byupdating the information.

Further, it is possible to provide a data distribution system and a datadistribution method enabling a content owner to directly control copyingas desired while using a standard apparatus as a processor after thereceiver.

Further, it is possible to provide a data receiver used in such acontent distribution system, receiving the distributed content data,performing adequate right processing, and outputting the content data ina usable manner.

Further, it is possible to provide a data provider and a data providingmethod for providing content data to be distributed in a state where theowner of the content can control the usage thereof.

Further, it is possible to provide a data transferer for transferringthe data provided in this way.

INDUSTRIAL APPLICABILITY

The present invention can be applied to a music distribution system fordistributing for example musical works via a network, hardware used forthat music distribution system, and data processing methods in thatmusic distribution system.

1. A transmitter for selectively transmitting a non-copy protectedcontent signal or a copyright protected processed content signal to aconnected receiver, comprising: transmission processing means forselectively processing a content signal for copyright protection,thereby producing a copyright protected processed content signal; logicmeans for determining by an authentication process whether a connectedreceiver is operable to function in accordance with copyright protectionencryption technology; transmission controlling means for holdinginformation indicating those receivers that are not enabled to copycontent by using either the content signal or the copyright protectedprocessed content signal and for controlling the signal transmitted bythe transmitter according to whether or not information indicating theconnected receiver is included in the held information, such that saidnon-copy protected content signal is transmitted if said connectedreceiver is not enabled to copy content; and means for monitoring for achange in connection of the receiver connected to said transmitter whilesaid non-copy protected content signal is being transmitted, to controlsaid transmitter to prohibit transmission of a non-copy protectedcontent signal and to change over to enable transmission of a copyrightprotected processed content signal when a change in the connectedreceiver is detected.
 2. A transmitter as set forth in claim 1, whereinsaid transmitter comprises a protection detecting means for determiningif said content is copyright protected; and wherein said transmissioncontrolling means controls the transmitted signal to be a copyrightprotected content signal when said protection detecting means determinesthat said content is copyright protected and to be a non-copyrightprotected content signal regardless of the determination by saidprotection detecting means when said information indicating theconnected receiver is included in said held information.
 3. Atransmitter as set forth in claim 1, wherein said transmissioncontrolling means controls said transmitter to transmit the copyrightprotected processed content signal instead of the non-copy protectedcontent signal so that said non-copy protected content signal is nottransmitted.
 4. A transmitter as set forth in claim 1, wherein saidtransmission controlling means holds information indicating saidreceiver in a tamper-proof updateable manner.
 5. A signal transmissionmethod for selectively transmitting a non-copyright protected contentsignal or a copyright protected content signal to a connected receiver,said method comprising the steps of: holding in a transmitterinformation indicating receivers that are not enabled to copy content ofa received content signal; deciding by an authentication process whetheror not a connected receiver is operable to function in accordance withcopyright protection encryption technology; controlling the transmittedsignal to be a non-copyright protected content signal or a copyrightprotected content signal according to whether or not informationindicating the connected receiver is included in the held information;monitoring for a change in connection of the connected receiver whiletransmitting a non-copyright protected content signal; and prohibitingthe transmission of said non-copyright protected content signal andchanging over to enable transmission of a copyright protected contentsignal when a change in the connected receiver is detected.
 6. A signaltransmission method as set forth in claim 5, further comprising thesteps of determining whether said content is copyright protected toproduce said copyright protected content signal and transmitting saidnon-copyright protected content signal even when it is determined thatsaid content is copyright protected when said information indicating theconnected receiver is included in said held information.
 7. A signaltransmission method as set forth in claim 5, wherein the copyrightprotected content signal is transmitted instead of the non-copyrightprotected content signal so as to prohibit the transmission of saidnon-copyright protected content signal.
 8. A transmitter for selectivelytransmitting a non-copy protected content signal or a copyrightprotected processed content signal to a connected receiver, comprising:a processor configured to selectively process a content signal forcopyright protection, thereby producing a copyright protected processedcontent signal; a logic unit configured to determine by anauthentication process whether a connected receiver is operable tofunction in accordance with copyright protection encryption technology;a controller configured to hold information indicating those receiversthat are not enabled to copy content by using either the content signalor the copyright protected processed content signal and to control thesignal transmitted by the transmitter according to whether or notinformation indicating the connected receiver is included in the heldinformation, such that said non-copy protected content signal istransmitted if said connected receiver is not enabled to copy content;and a monitor configured to monitor a change in connection of thereceiver connected to said transmitter while said non-copy protectedcontent signal is being transmitted, to control said transmitter toprohibit the transmission of a non-copy protected content signal and tochange over to enable transmission of a copyright protected processedcontent signal when a change in the connected receiver is detected.